Opencart Product Page SQL error syntax 1064

I’ve got a website with OpenCart 1.5.6.1 and when I’m logged as a customer and I want see some product page, I get this error:

Error: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'op LEFT JOIN ad_`order` o ON (op.order_id = o.order_id) WHERE o.customer_id = '3' at line 1
Error No: 1064
SELECT COUNT(*) AS total FROM ad_`order_product` op LEFT JOIN ad_`order` o ON (op.order_id = o.order_id) WHERE o.customer_id = '35' AND op.product_id = '83'AND o.order_status_id = '5'
in /web/htdocs/www.adtecno.com/home/system/database/mysql.php on line 50

I really cannot find a solution, anyone could please help me out? Thanks a lot!